Crash on multi module project when ``benchmark`` is set and parallel building is active

### Affected version

3.7.0

### Bug description

When ``true`` is set on a mult-maven module project and I run ``mvn test pmd:aggregate-pmd-no-fork pmd:check -T2C`` (parallel building active!) the following crash happens:

(cleaned up version because the error is present like 6 times and everything overlaps)
```
Using the MultiThreadedBuilder implementation with a thread count of 32
...
[INFO] >>> pmd:3.27.0:check (default-cli) > :pmd @ integration-tests >>>
[INFO]
[INFO] >>> pmd:3.27.0:check (default-cli) > :pmd @ domain >>>
[INFO]
...
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for redacted 4.0.0-SNAPSHOT:
[INFO]
[INFO] redacted ........................................... SUCCESS [ 0.023 s]
[INFO] domain ............................................. FAILURE [ 1.332 s]
[INFO] domain-metamodel ................................... SUCCESS [ 2.580 s]
[INFO] infrastructure-persistence ......................... SUCCESS [ 1.474 s]
[INFO] session-api ........................................ FAILURE [ 1.241 s]
[INFO] xxxxxxxxxxxx ....................................... SUCCESS [ 0.119 s]
[INFO] application ........................................ SUCCESS [ 1.311 s]
[INFO] external-connector ................................. SUCCESS [ 1.019 s]
[INFO] webapp-dev-xxxxxx .................................. FAILURE [ 1.235 s]
[INFO] xxxxxx-spring-boot-starter-optimized ............... SUCCESS [ 0.496 s]
[INFO] xxxxxx-shared-meta ................................. FAILURE [ 1.239 s]
[INFO] xxxxxx-shared ...................................... SUCCESS [ 0.144 s]
[INFO] external-connector-xxxxxx-ui ....................... SUCCESS [ 0.795 s]
[INFO] integration-tests .................................. SUCCESS [ 0.028 s]
[INFO] tci-db ............................................. SUCCESS [ 0.577 s]
[INFO] infrastructure-persistence-testcontainers .......... SUCCESS [ 0.873 s]
[INFO] xxxx-api-client .................................... SUCCESS [ 1.271 s]
[INFO] tci-xxxx ........................................... SUCCESS [ 0.204 s]
[INFO] tci-redacted-webapp ................................ FAILURE [ 1.212 s]
[INFO] xxxxxxxxxxxx-xxxx .................................. SUCCESS [ 0.613 s]
[INFO] webapp-meta ........................................ SUCCESS [ 0.090 s]
[INFO] webapp-xxxx-elements ............................... SUCCESS [ 0.136 s]
[INFO] webapp-xxxx ........................................ SUCCESS [ 1.101 s]
[INFO] xxxxxxxxxxxx-xxxx-xxxxxx-ui ........................ SUCCESS [ 0.833 s]
[INFO] timetracker ........................................ SUCCESS [ 0.104 s]
[INFO] timetracker-xxxxxxx ................................ SUCCESS [ 0.088 s]
[INFO] timetracker-xxxxxxx-xxxxxx-ui ...................... SUCCESS [ 0.672 s]
[INFO] xxxxxx-xxxxx-plugin ................................ SUCCESS [ 3.711 s]
[INFO] webapp ............................................. SUCCESS [ 4.698 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 20.960 s (Wall Clock)
[INFO] Finished at: 2025-08-28T09:37:29+02:00
[INFO] ------------------------------------------------------------------------
...
Failed to execute goal org.apache.maven.plugins:maven-pmd-plugin:3.27.0:pmd (pmd) on project domain: Execution pmd of goal org.apache.maven.plugins:maven-pmd-plugin:3.27.0:pmd failed: Cannot invoke "net.sourceforge.pmd.benchmark.TimingReport.getLabeledMeasurements(net.sourceforge.pmd.benchmark.TimedOperationCategory)" because "report" is null
Caused by: java.lang.NullPointerException: Cannot invoke "net.sourceforge.pmd.benchmark.TimingReport.getLabeledMeasurements(net.sourceforge.pmd.benchmark.TimedOperationCategory)" because "report" is null
at net.sourceforge.pmd.benchmark.TextTimingReportRenderer.render (TextTimingReportRenderer.java:43)
at org.apache.maven.plugins.pmd.exec.PmdExecutor.writeBenchmarkReport (PmdExecutor.java:274)
at org.apache.maven.plugins.pmd.exec.PmdExecutor.run (PmdExecutor.java:206)
at org.apache.maven.plugins.pmd.exec.PmdServiceExecutor.execute (PmdServiceExecutor.java:54)
at org.apache.maven.plugins.pmd.PmdReport.executePmd (PmdReport.java:373)
at org.apache.maven.plugins.pmd.PmdReport.canGenerateReport (PmdReport.java:327)
at org.apache.maven.reporting.AbstractMavenReport.execute (AbstractMavenReport.java:200)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:126)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:328)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:316)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:212)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:174)
at org.apache.maven.lifecycle.internal.MojoExecutor.access$000 (MojoExecutor.java:75)
at org.apache.maven.lifecycle.internal.MojoExecutor$1.run (MojoExecutor.java:162)
at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute (DefaultMojosExecutionStrategy.java:39)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:159)
at org.apache.maven.lifecycle.internal.MojoExecutor.executeForkedExecutions (MojoExecutor.java:448)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:311)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:212)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:174)
at org.apache.maven.lifecycle.internal.MojoExecutor.access$000 (MojoExecutor.java:75)
at org.apache.maven.lifecycle.internal.MojoExecutor$1.run (MojoExecutor.java:162)
at org.apache.maven.plugin.DefaultMojosExecutionStrategy.execute (DefaultMojosExecutionStrategy.java:39)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:159)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:105)
at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder$1.call (MultiThreadedBuilder.java:193)
at org.apache.maven.lifecycle.internal.builder.multithreaded.MultiThreadedBuilder$1.call (MultiThreadedBuilder.java:180)
at java.util.concurrent.FutureTask.run (FutureTask.java:317)
at java.util.concurrent.Executors$RunnableAdapter.call (Executors.java:572)
at java.util.concurrent.FutureTask.run (FutureTask.java:317)
at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1144)
at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:642)
at java.lang.Thread.run (Thread.java:1583)
```

The problem is not present when parallel building is disabled.