internal/lsp/source: enable type error analyzers

I had intended to enable these after gopls/v0.4.0 was released so that
people who test at master can try these out. Also, mark "fillreturns" as
high confidence so users can get it applied on save, much like
goreturns.

Change-Id: I71aa0b723b2e9b69474ceed7cb1d7da7c929d65d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/228724
Run-TryBot: Rebecca Stambler <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Robert Findley <[email protected]>

Author: stamblerre

internal/lsp/source/options.go

@@ -498,23 +498,24 @@ func (r *OptionResult) setBool(b *bool) {
 func typeErrorAnalyzers() map[string]Analyzer {
 	return map[string]Analyzer{
 		fillreturns.Analyzer.Name: {
-			Analyzer:   fillreturns.Analyzer,
-			enabled:    false,
-			FixesError: fillreturns.FixesError,
+			Analyzer:       fillreturns.Analyzer,
+			enabled:        true,
+			FixesError:     fillreturns.FixesError,
+			HighConfidence: true,
 		},
 		nonewvars.Analyzer.Name: {
 			Analyzer:   nonewvars.Analyzer,
-			enabled:    false,
+			enabled:    true,
 			FixesError: nonewvars.FixesError,
 		},
 		noresultvalues.Analyzer.Name: {
 			Analyzer:   noresultvalues.Analyzer,
-			enabled:    false,
+			enabled:    true,
 			FixesError: noresultvalues.FixesError,
 		},
 		undeclaredname.Analyzer.Name: {
 			Analyzer:   undeclaredname.Analyzer,
-			enabled:    false,
+			enabled:    true,
 			FixesError: undeclaredname.FixesError,
 		},
 	}