Fixed weird error message in core install if invalid platform is spcified (#2309)

* Fixed weird error message in 'core install' if invalid platform is specified

* Fixed integration test

Author: cmaglie

Diff for: arduino/errors.go

@@ -837,11 +837,8 @@ type MultiplePlatformsError struct {
 }
 
 func (e *MultiplePlatformsError) Error() string {
-	return tr("Found %d platform for reference \"%s\":\n%s",
-		len(e.Platforms),
-		e.UserPlatform,
-		strings.Join(e.Platforms, "\n"),
-	)
+	return tr("Found %d platforms matching \"%s\": %s",
+		len(e.Platforms), e.UserPlatform, strings.Join(e.Platforms, ", "))
 }
 
 // ToRPCStatus converts the error into a *status.Status

Diff for: internal/cli/arguments/reference.go

@@ -116,11 +116,13 @@ func ParseReference(arg string) (*Reference, error) {
 	}
 	// replace the returned Reference only if only one occurrence is found,
 	// otherwise return an error to the user because we don't know on which platform operate
-	if len(foundPlatforms) == 1 {
-		ret.PackageName = toks[0]
-		ret.Architecture = toks[1]
-	} else {
+	if len(foundPlatforms) == 0 {
+		return nil, &arduino.PlatformNotFoundError{Platform: arg}
+	}
+	if len(foundPlatforms) > 1 {
 		return nil, &arduino.MultiplePlatformsError{Platforms: foundPlatforms, UserPlatform: arg}
 	}
+	ret.PackageName = toks[0]
+	ret.Architecture = toks[1]
 	return ret, nil
 }

Diff for: internal/integrationtest/core/core_test.go

@@ -883,7 +883,7 @@ func TestCoreDownloadMultiplePlatforms(t *testing.T) {
 	// The cli should not allow it since optimizing the casing results in finding two cores
 	_, stderr, err := cli.Run("core", "upgrade", "Packager:Arch")
 	require.Error(t, err)
-	require.Contains(t, string(stderr), "Invalid argument passed: Found 2 platform for reference")
+	require.Contains(t, string(stderr), "Invalid argument passed: Found 2 platforms matching")
 }
 
 func TestCoreWithMissingCustomBoardOptionsIsLoaded(t *testing.T) {