On uploading: `Exception in thread "Thread-5" java.lang.NullPointerException: Cannot invoke "String.length()" because "s" is null`

Exception in thread "Thread-5" java.lang.NullPointerException: Cannot invoke "String.length()" because "s" is null
	at java.base/java.net.URLEncoder.encode(URLEncoder.java:223)
	at java.base/java.net.URLEncoder.encode(URLEncoder.java:194)
	at org.wikidata.wdtk.wikibaseapi.ApiConnection.getQueryString(ApiConnection.java:588)
	at org.wikidata.wdtk.wikibaseapi.ApiConnection.sendRequest(ApiConnection.java:434)
	at org.wikidata.wdtk.wikibaseapi.ApiConnection.sendJsonRequest(ApiConnection.java:399)
	at org.openrefine.wikibase.editing.MediaFileUtils.uploadFile(MediaFileUtils.java:349)
	at org.openrefine.wikibase.editing.MediaFileUtils.uploadRemoteFile(MediaFileUtils.java:254)
	at org.openrefine.wikibase.updates.MediaInfoEdit.uploadFile(MediaInfoEdit.java:288)
	at org.openrefine.wikibase.editing.EditBatchProcessor.performEdit(EditBatchProcessor.java:232)
	at org.openrefine.wikibase.operations.PerformWikibaseEditsOperation$PerformEditsProcess.run(PerformWikibaseEditsOperation.java:334)
	at java.base/java.lang.Thread.run(Thread.java:1583)

OpenRefine 3.9.3
CommonsExtension 0.1.3

java --version
openjdk 21.0.6 2025-01-21 LTS
OpenJDK Runtime Environment Temurin-21.0.6+7 (build 21.0.6+7-LTS)
OpenJDK 64-Bit Server VM Temurin-21.0.6+7 (build 21.0.6+7-LTS, mixed mode, sharing)

Maybe this is because my schema is invalid? Is it a correct way to upload changes back to Commons?

Start at MediaFileUtils.uploadFile line 349 and follow the request into ApiConnection.getQueryString line 588, where the stack trace shows the null value reaching URL encoding. Reproduce the Commons upload with the reported OpenRefine 3.9.3 and CommonsExtension 0.1.3 setup, then determine which upload input is missing and verify that the failure is handled or prevented.