NPE when running lint

**Gradle task**: `lint`
**Timber version**: `4.6.1`
**Result**:
```
java.lang.NullPointerException
at timber.lint.WrongTimberUsageDetector.checkNestedStringFormat(WrongTimberUsageDetector.java:108)
at timber.lint.WrongTimberUsageDetector.visitMethod(WrongTimberUsageDetector.java:71)
at com.android.tools.lint.client.api.UElementVisitor$DelegatingPsiVisitor.visitMethodCallExpression(UElementVisitor.java:1065)
at com.android.tools.lint.client.api.UElementVisitor$DelegatingPsiVisitor.visitCallExpression(UElementVisitor.java:1046)
at org.jetbrains.uast.UCallExpression$DefaultImpls.accept(UCallExpression.kt:99)
at org.jetbrains.uast.java.JavaUCallExpression.accept(javaUCallExpressions.kt:23)
at org.jetbrains.uast.UQualifiedReferenceExpression$DefaultImpls.accept(UQualifiedReferenceExpression.kt:48)
at org.jetbrains.uast.java.JavaUCompositeQualifiedExpression.accept(JavaUCompositeQualifiedExpression.kt:22)
at org.jetbrains.uast.internal.ImplementationUtilsKt.acceptList(implementationUtils.kt:23)
at org.jetbrains.uast.UCallExpression$DefaultImpls.accept(UCallExpression.kt:103)
at org.jetbrains.uast.java.JavaUCallExpression.accept(javaUCallExpressions.kt:23)
at org.jetbrains.uast.UQualifiedReferenceExpression$DefaultImpls.accept(UQualifiedReferenceExpression.kt:48)
at org.jetbrains.uast.java.JavaUCompositeQualifiedExpression.accept(JavaUCompositeQualifiedExpression.kt:22)
at org.jetbrains.uast.internal.ImplementationUtilsKt.acceptList(implementationUtils.kt:23)
at org.jetbrains.uast.UCallExpression$DefaultImpls.accept(UCallExpression.kt:103)
at org.jetbrains.uast.java.JavaUCallExpression.accept(javaUCallExpressions.kt:23)
at org.jetbrains.uast.UQualifiedReferenceExpression$DefaultImpls.accept(UQualifiedReferenceExpression.kt:48)
at org.jetbrains.uast.java.JavaUCompositeQualifiedExpression.accept(JavaUCompositeQualifiedExpression.kt:22)
at org.jetbrains.uast.internal.ImplementationUtilsKt.acceptList(implementationUtils.kt:23)
at org.jetbrains.uast.UCallExpression$DefaultImpls.accept(UCallExpression.kt:103)
at org.jetbrains.uast.java.JavaUCallExpression.accept(javaUCallExpressions.kt:23)
at org.jetbrains.uast.UQualifiedReferenceExpression$DefaultImpls.accept(UQualifiedReferenceExpression.kt:48)
at org.jetbrains.uast.java.JavaUCompositeQualifiedExpression.accept(JavaUCompositeQualifiedExpression.kt:22)
at org.jetbrains.uast.internal.ImplementationUtilsKt.acceptList(implementationUtils.kt:23)
at org.jetbrains.uast.UBlockExpression$DefaultImpls.accept(UBlockExpression.kt:35)
at org.jetbrains.uast.java.JavaUBlockExpression.accept(JavaUBlockExpression.kt:22)
at org.jetbrains.uast.UIfExpression$DefaultImpls.accept(UIfExpression.kt:73)
at org.jetbrains.uast.java.JavaUIfExpression.accept(JavaUIfExpression.kt:24)
at org.jetbrains.uast.internal.ImplementationUtilsKt.acceptList(implementationUtils.kt:23)
at org.jetbrains.uast.UBlockExpression$DefaultImpls.accept(UBlockExpression.kt:35)
at org.jetbrains.uast.java.JavaUCodeBlockExpression.accept(JavaUCodeBlockExpression.kt:22)
at org.jetbrains.uast.UMethod$DefaultImpls.accept(UMethod.kt:53)
at org.jetbrains.uast.java.JavaUMethod.accept(JavaUMethod.kt:25)
at org.jetbrains.uast.internal.ImplementationUtilsKt.acceptList(implementationUtils.kt:23)
at org.jetbrains.uast.UClass$DefaultImpls.accept(UClass.kt:63)
at org.jetbrains.uast.java.AbstractJavaUClass.accept(JavaUClass.kt:26)
at org.jetbrains.uast.internal.ImplementationUtilsKt.acceptList(implementationUtils.kt:23)
at org.jetbrains.uast.UFile$DefaultImpls.accept(UFile.kt:87)
at org.jetbrains.uast.java.JavaUFile.accept(JavaUFile.kt:27)
at com.android.tools.lint.client.api.UElementVisitor.lambda$visitFile$6(UElementVisitor.java:248)
at com.android.tools.lint.client.api.LintClient.runReadAction(LintClient.kt:1482)
at com.android.tools.lint.client.api.LintDriver$LintClientWrapper.runReadAction(LintDriver.kt:2108)
at com.android.tools.lint.client.api.UElementVisitor.visitFile(UElementVisitor.java:244)
at com.android.tools.lint.client.api.LintDriver$visitJavaFiles$1.run(LintDriver.kt:1532)
at com.android.tools.lint.client.api.LintClient.runReadAction(LintClient.kt:1482)
at com.android.tools.lint.client.api.LintDriver$LintClientWrapper.runReadAction(LintDriver.kt:2108)
at com.android.tools.lint.client.api.LintDriver.visitJavaFiles(LintDriver.kt:1532)
at com.android.tools.lint.client.api.LintDriver.visitJavaFiles(LintDriver.kt:1491)
at com.android.tools.lint.client.api.LintDriver.checkJava(LintDriver.kt:1469)
at com.android.tools.lint.client.api.LintDriver.runFileDetectors(LintDriver.kt:1025)
at com.android.tools.lint.client.api.LintDriver.checkProject(LintDriver.kt:882)
at com.android.tools.lint.client.api.LintDriver.analyze(LintDriver.kt:385)
at com.android.tools.lint.LintCliClient.run(LintCliClient.java:155)
at com.android.build.gradle.internal.LintGradleClient.run(LintGradleClient.java:197)
at com.android.build.gradle.tasks.LintBaseTask.runLint(LintBaseTask.java:198)
at com.android.build.gradle.tasks.LintPerVariantTask.lintSingleVariant(LintPerVariantTask.java:53)
at com.android.build.gradle.tasks.LintPerVariantTask.lint(LintPerVariantTask.java:45)
at sun.reflect.GeneratedMethodAccessor1210.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73)
at org.gradle.api.internal.project.taskfactory.StandardTaskAction.doExecute(StandardTaskAction.java:46)
at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:39)
at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:26)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:788)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:755)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$1.run(ExecuteActionsTaskExecuter.java:124)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:199)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:110)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:113)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:95)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:73)
at org.gradle.api.internal.tasks.execution.OutputDirectoryCreatingTaskExecuter.execute(OutputDirectoryCreatingTaskExecuter.java:51)
at org.gradle.api.internal.tasks.execution.SkipCachedTaskExecuter.execute(SkipCachedTaskExecuter.java:103)
at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:59)
at org.gradle.api.internal.tasks.execution.ResolveTaskOutputCachingStateExecuter.execute(ResolveTaskOutputCachingStateExecuter.java:54)
at org.gradle.api.internal.tasks.execution.ResolveBuildCacheKeyExecuter.execute(ResolveBuildCacheKeyExecuter.java:63)
at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:59)
at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:101)
at org.gradle.api.internal.tasks.execution.FinalizeInputFilePropertiesTaskExecuter.execute(FinalizeInputFilePropertiesTaskExecuter.java:44)
at org.gradle.api.internal.tasks.execution.CleanupStaleOutputsExecuter.execute(CleanupStaleOutputsExecuter.java:88)
at org.gradle.api.internal.tasks.execution.ResolveTaskArtifactStateTaskExecuter.execute(ResolveTaskArtifactStateTaskExecuter.java:62)
at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:54)
at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:34)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker$1.run(DefaultTaskGraphExecuter.java:248)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:199)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:110)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:241)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:230)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker.processTask(DefaultTaskPlanExecutor.java:123)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker.access$200(DefaultTaskPlanExecutor.java:79)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker$1.execute(DefaultTaskPlanExecutor.java:104)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker$1.execute(DefaultTaskPlanExecutor.java:98)
at org.gradle.execution.taskgraph.DefaultTaskExecutionPlan.execute(DefaultTaskExecutionPlan.java:623)
at org.gradle.execution.taskgraph.DefaultTaskExecutionPlan.executeWithTask(DefaultTaskExecutionPlan.java:578)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker.run(DefaultTaskPlanExecutor.java:98)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63)
at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:46)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:55)
at java.lang.Thread.run(Thread.java:748)

```

I was under the impression that https://github.com/JakeWharton/timber/pull/278 was supposed to fix this.