lint: Fix typeassert and case exhaustive warnings

.golangci.yml

@@ -30,6 +30,8 @@ linters-settings:
       - rela
       - equalisation
       - synchronisation
+  exhaustive:
+    default-signifies-exhaustive: true
   gosec:
     excludes:
       # allow md5

internal/shquote/shquote.go

@@ -39,6 +39,8 @@ func Parse(s string) []Token {
 			sb.WriteRune(r)
 			ss = doubleQuote
 			continue
+		default:
+			// nop
 		}
 
 		switch r {
@@ -107,6 +109,8 @@ func Parse(s string) []Token {
 			case whitespace:
 				ss = word
 				start = i
+			default:
+				// nop
 			}
 			sb.WriteRune(r)
 		}
@@ -115,6 +119,8 @@ func Parse(s string) []Token {
 		switch ss {
 		case word, singleQuote, doubleQuote:
 			tokens = append(tokens, Token{Start: start, End: len(s), Str: sb.String()})
+		default:
+			// nop
 		}
 	}
 	tokens = append(tokens, Token{Separator: true})

pkg/decode/decode.go

@@ -989,7 +989,11 @@ func (d *D) TryFieldScalarFn(name string, sfn scalar.Fn, sms ...scalar.Mapper) (
 	if err != nil {
 		return &scalar.S{}, err
 	}
-	return v.V.(*scalar.S), nil
+	sr, ok := v.V.(*scalar.S)
+	if !ok {
+		panic("not a scalar value")
+	}
+	return sr, nil
 }
 
 func (d *D) FieldScalarFn(name string, sfn scalar.Fn, sms ...scalar.Mapper) *scalar.S {

pkg/interp/interp.go

@@ -965,10 +965,17 @@ func (i *Interp) lookupState(key string) interface{} {
 }
 
 func (i *Interp) includePaths() []string {
-	pathsAny, _ := i.lookupState("include_paths").([]interface{})
+	pathsAny, ok := i.lookupState("include_paths").([]interface{})
+	if !ok {
+		panic("include_paths not slice")
+	}
 	var paths []string
 	for _, pathAny := range pathsAny {
-		paths = append(paths, pathAny.(string))
+		path, ok := pathAny.(string)
+		if !ok {
+			panic("path not string")
+		}
+		paths = append(paths, path)
 	}
 	return paths
 }