API registerCallHierarchyProvider does not work as expected and flakily

• VSCode Version: 1.52.1
• OS Version: MacOs 10.15.6

Steps to Reproduce: I have an extension (repo here:https://github.com/coolcorexix/jsx-viewer-extension) that use vscode.languages.registerCallHierarchyProvider to process the JSX tree in a file. When I call the ‘peekHierarchyCall’ action in a plaintext file it works stably and always jump to the breakpoint of TestHierarchyProvider (path: src/vscode-components/test-hierachy-provider.ts).

But in the context of ts/tsx/js/jsx files, about half of the time it use another unexpected Hierarchy Provider and does not jump to code of the test-hierachy-provider.ts file. I wonder if this is a buggy behaviour or is there any default provider in VsCode app that run on some conditions that I am not aware of.

Does this issue occur when all extensions are disabled?: Yes

[phatNfqAsia]

@jrieken I figured out the reason, if I set the selector for the provider to detect on language: js, it will not be register if I turned off the Javascript Basic Builtin Extension. But it worked with

vscode.languages.registerCallHierarchyProvider({
		scheme: 'file',
		pattern: '**/*.jsx',
	}, new TestHierarchyProvider());

then the peekHierarchyCall is available. so I confirmed this is caused by BuiltIn extension for JS/TS language. But is there anyway I can make my Extension work stably while turning on these built in extensions?

[coolcorexix]

@jrieken what can I help to make this fixed?