gopls/internal/lsp/cache: suppress crashes in fact_purity analyzer

It has a known bug, and the purpose of the PanicOnBugs is to
find unknown bugs.

Updates golang/go#54762
Updates golang/go#56035

Change-Id: Id9fdfff478ef52b1d864acee366991808baeb574
Reviewed-on: https://go-review.googlesource.com/c/tools/+/440178
Run-TryBot: Alan Donovan <[email protected]>
Reviewed-by: Robert Findley <[email protected]>
gopls-CI: kokoro <[email protected]>

Author: adonovan

gopls/internal/lsp/cache/analysis.go

@@ -365,8 +365,10 @@ func actionImpl(ctx context.Context, snapshot *snapshot, deps []*actionHandle, a
 			if r := recover(); r != nil {
 				// An Analyzer crashed. This is often merely a symptom
 				// of a problem in package loading.
-				if bug.PanicOnBugs {
+				if bug.PanicOnBugs && analyzer.Name != "fact_purity" {
 					// During testing, crash. See issues 54762, 56035.
+					// But ignore analyzers with known crash bugs:
+					// - fact_purity (dominikh/go-tools#1327)
 					debug.SetTraceback("all") // show all goroutines
 					panic(r)
 				} else {