Refactor subproject discovery code

Subproject discovery must be done under any circumstances. Previously, there was duplicate code to do this for both file project paths and folder project paths, resulting in the code being more difficult to maintain.

In order to accomodate this change, the error message in the event of no projects being discovered was reworded to be applicable to either project path type.

Author: per1234

Diff for: internal/project/project.go

@@ -53,7 +53,7 @@ func FindProjects() ([]Type, error) {
 
 // findProjects handles the recursion for FindProjects().
 func findProjects(targetPath *paths.Path) ([]Type, error) {
-	var foundProjects []Type
+	var foundParentProjects []Type
 
 	// If targetPath is a file, targetPath itself is the project, so it's only necessary to determine/verify the type.
 	if targetPath.IsNotDir() {
@@ -82,39 +82,33 @@ func findProjects(targetPath *paths.Path) ([]Type, error) {
 				ProjectType:      projectType,
 				SuperprojectType: projectType,
 			}
-			foundProjects = append(foundProjects, foundProject)
-
-			foundProjects = append(foundProjects, findSubprojects(foundProject, projectType)...)
-
-			return foundProjects, nil
+			foundParentProjects = append(foundParentProjects, foundProject)
 		}
-
-		return nil, fmt.Errorf("Specified path %s is not an Arduino project", targetPath)
-	}
-
-	var foundParentProjects []Type
-	if configuration.SuperprojectTypeFilter() == projecttype.All || configuration.Recursive() {
-		// Project discovery and/or type detection is required.
-		foundParentProjects = findProjectsUnderPath(targetPath, configuration.SuperprojectTypeFilter(), configuration.Recursive())
 	} else {
-		// Project was explicitly defined by user.
-		foundParentProjects = append(foundParentProjects,
-			Type{
-				Path:             targetPath,
-				ProjectType:      configuration.SuperprojectTypeFilter(),
-				SuperprojectType: configuration.SuperprojectTypeFilter(),
-			},
-		)
+		if configuration.SuperprojectTypeFilter() == projecttype.All || configuration.Recursive() {
+			// Project discovery and/or type detection is required.
+			foundParentProjects = findProjectsUnderPath(targetPath, configuration.SuperprojectTypeFilter(), configuration.Recursive())
+		} else {
+			// Project was explicitly defined by user.
+			foundParentProjects = append(foundParentProjects,
+				Type{
+					Path:             targetPath,
+					ProjectType:      configuration.SuperprojectTypeFilter(),
+					SuperprojectType: configuration.SuperprojectTypeFilter(),
+				},
+			)
+		}
 	}
 
 	// Discover subprojects of all found projects.
+	var foundProjects []Type
 	for _, foundParentProject := range foundParentProjects {
 		foundProjects = append(foundProjects, foundParentProject)
 		foundProjects = append(foundProjects, findSubprojects(foundParentProject, foundParentProject.ProjectType)...)
 	}
 
 	if foundProjects == nil {
-		return nil, fmt.Errorf("No projects found under %s", targetPath)
+		return nil, fmt.Errorf("No projects found with project path %s", targetPath)
 	}
 
 	return foundProjects, nil