Creating a new .qs file in a project folder where the qsharp.json has files list triggers panic

[swernli]

When editing a Q# project that has an explicit files list in the qsharp.json, if you create a new .qs file in the src folder before adding it to the explicit files list the language service panics:

2025-01-06 12:34:24.024 [error] [wasm] Wasm panic occurred: panicked at language_service/src/compilation.rs:297:14:
source should exist in the user source map

Stack:

Error: 
	at imports.wbg.__wbg_new_0232637a3cb0b1a7 (file:///Users/swernli/.vscode/extensions/quantum.qsharp-lang-vscode-dev-1.12.2/out/extension.js#vscode-extension:32866:17)
	at wasm://wasm/00e6c39a:wasm-function[3681]:0x312e28
	at wasm://wasm/00e6c39a:wasm-function[2061]:0x2c84c4
	at wasm://wasm/00e6c39a:wasm-function[2834]:0x2fe7b4
	at wasm://wasm/00e6c39a:wasm-function[2726]:0x2faeb5
	at wasm://wasm/00e6c39a:wasm-function[1851]:0x2a8fac
	at LanguageService.get_code_lenses (file:///Users/swernli/.vscode/extensions/quantum.qsharp-lang-vscode-dev-1.12.2/out/extension.js#vscode-extension:32709:12)
	at QSharpLanguageService.getCodeLenses (file:///Users/swernli/.vscode/extensions/quantum.qsharp-lang-vscode-dev-1.12.2/out/extension.js#vscode-extension:33815:33)
	at QSharpCodeLensProvider.provideCodeLenses (file:///Users/swernli/.vscode/extensions/quantum.qsharp-lang-vscode-dev-1.12.2/out/extension.js#vscode-extension:39781:51)
	at mf.provideCodeLenses (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:121:200273)
	at vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:121:229194
	at Rt.s (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:121:228034)
	at Rt.$provideCodeLenses (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:121:229182)
	at N0.S (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:30:77539)
	at N0.Q (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:30:77319)
	at N0.M (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:30:76370)
	at N0.L (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:30:75513)
	at tu.value (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:30:74310)
	at C.B (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:29:746)
	at C.fire (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:29:964)
	at GN.e.port1.onmessage (vscode-file://vscode-app/Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/worker/extensionHostWorkerMain.js:145:3409)

Somehow this case should fail gracefully, ideally with feedback to the user that the file is not part of the project and won't be included in any compilation. Stretch goal could be a quick fix to put it into the files list from within that new file, but could also be just a warning that the file is not included (similar to how rust-analyzer does it).