[devtools] [repl] Do not print character number of error

The character number reported by Yaegi (where the error occurred) is always wrong. It will be better to simply hide this information from the user.

devtools/internal/interpreter/interpreter.go

@@ -225,7 +225,7 @@ func (i Instance) runGoCode(source string) (r EvalResult, e error) {
 		err := recover()
 		if err != nil {
 			r = GoCodeExecuted
-			e = fmt.Errorf("panic when running Yaegi: %s", err)
+			e = fmt.Errorf("panic when running Yaegi Go interpreter: %s", err)
 		}
 	}()
 
@@ -244,14 +244,37 @@ func (i Instance) runGoCode(source string) (r EvalResult, e error) {
 			return Continued, nil
 		}
 
-		return GoCodeExecuted, err
+		return GoCodeExecuted, convertYaegiError(err)
 	}
 
 	printResult(res)
 
 	return GoCodeExecuted, nil
 }
 
+var (
+	yaegiCfgErrorPattern     = regexp.MustCompile(`^(\d+:)(\d+:)(.*)`) // control flow graph generation error
+	yaegiScannerErrorPattern = regexp.MustCompile(`^_\.go:(\d+:)(\d+:)(.*)`)
+)
+
+// Yaegi reports wrong character number in error messages. It is better to remove this information completely.
+func convertYaegiError(err error) error {
+	errStr := err.Error()
+
+	switch {
+	case yaegiCfgErrorPattern.MatchString(errStr):
+		return fmt.Errorf(
+			yaegiCfgErrorPattern.ReplaceAllString(errStr, "$1$3"),
+		)
+	case yaegiScannerErrorPattern.MatchString(errStr):
+		return fmt.Errorf(
+			yaegiScannerErrorPattern.ReplaceAllString(errStr, "$1$3"),
+		)
+	default:
+		return err
+	}
+}
+
 // shouldContinueOnError returns true if the error can be safely ignored
 // to let the caller grab one more line before retrying to parse its input.
 func shouldContinueOnError(err error, source string) bool {

devtools/internal/interpreter/interpreter_test.go

@@ -249,6 +249,37 @@ func TestEval(t *testing.T) {
 		require.NoError(t, err)
 		assert.Equal(t, "interpreter_test.anotherType: {}\n", swapper.ReadOutput(t))
 	})
+
+	t.Run("should convert error message to exclude invalid character number", func(t *testing.T) {
+		tests := map[string]struct {
+			source             string
+			expectedErrMessage string
+		}{
+			"undefined": {
+				source:             "undefinedVar",
+				expectedErrMessage: "1: undefined: undefinedVar",
+			},
+			"undefined in second line": {
+				source:             "{ \n undefinedVar \n }",
+				expectedErrMessage: "2: undefined: undefinedVar",
+			},
+			"invalid number literal": {
+				source:             "a := 123a123",
+				expectedErrMessage: "1: expected ';', found a123 (and 1 more errors)",
+			},
+			"invalid number literal in second line": {
+				source:             "{ \n a := 123a123 \n }",
+				expectedErrMessage: "2: expected ';', found a123 (and 1 more errors)",
+			},
+		}
+		for name, testCase := range tests {
+			t.Run(name, func(t *testing.T) {
+				_, err := newInterpreterInstance(t).Eval(testCase.source)
+				require.Error(t, err)
+				assert.Equal(t, testCase.expectedErrMessage, err.Error())
+			})
+		}
+	})
 }
 
 func TestExport(t *testing.T) {