FileSystemWatcherManager crashes with FileSystemNotFoundException when workspace contains non-file URI projects

[xinyi-gong]

Environment:

• LSP4E version: (0.19.7)
• Eclipse: 2025-03
• OS: Windows

Description:

When a workspace contains a project with a non-file URI scheme (e.g. SAP ABAP projects using semanticfs://), opening any file that is mapped to a language server via contentTypeMapping (e.g. a .md file matched by TM4E Language Pack's markdown content type) causes an unhandled FileSystemNotFoundException.

The error is thrown from FileSystemWatcherManager's constructor

Stack Trace:

org.eclipse.e4.core.di.InjectionException: java.nio.file.FileSystemNotFoundException: Provider "semanticfs" not installed
    at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:68)
    ...
Caused by: java.nio.file.FileSystemNotFoundException: Provider "semanticfs" not installed
    at java.base/java.nio.file.Path.of(Path.java:213)
    at java.base/java.nio.file.Paths.get(Paths.java:98)
    at org.eclipse.lsp4e.internal.files.FileSystemWatcherManager.<init>(FileSystemWatcherManager.java:57)
    at org.eclipse.lsp4e.LanguageServerWrapper.<init>(LanguageServerWrapper.java:328)
    at org.eclipse.lsp4e.LanguageServiceAccessor.getLSWrappers(LanguageServiceAccessor.java:339)
    at org.eclipse.lsp4e.LanguageServers$LanguageServerDocumentExecutor.getServers(LanguageServers.java:289)
    at org.eclipse.lsp4e.internal.LSPDocumentAbstractHandler$LanguageServerDocumentHandlerExecutor.anyMatching(LSPDocumentAbstractHandler.java:59)
    at org.eclipse.lsp4e.internal.LSPDocumentAbstractHandler.setEnabled(LSPDocumentAbstractHandler.java:123)
    at org.eclipse.lsp4e.operations.rename.LSPRenameHandler.setEnabled(LSPRenameHandler.java:79)

Steps to Reproduce:

1. Open a workspace containing a project with a non-file URI scheme (e.g. SAP ABAP with semanticfs://)
2. Have TM4E Language Pack installed (provides org.eclipse.tm4e.language_pack.markdown content type with an LSP4E language server mapping)
3. Open any .md file using any TextEditor-based editor (including "Open With → Plain Text Editor")
4. FileSystemNotFoundException appears in the Error Log

We're hitting this in our plugin because we need to open .md files in workspaces that contain SAP ABAP projects (semanticfs://). Would it be possible to add a scheme check in FileSystemWatcherManager to skip non-file schema projects?