Handle empty relative path case in HP.AsString()

Return '.' when HierarchyPath is empty and prefix is false.

utils/coreutils.go

@@ -647,18 +647,20 @@ func (hP HierarchyPath) AsString(sep string, prefix bool) string {
 	var strHP strings.Builder
 
 	// If prefix is true and the HierarchyPath slice is empty, sep will be returned.
+	// This will indicate the start of the absolute path.
 	if prefix {
 		strHP.WriteString(sep)
 	}
 
-	// TODO: Since this function can convert both the full and the relative HierarchyPath to a string, with
-	// prefix telling us which is which (true -> full path, false -> relative path), we should consider
-	// returning the '.' character when prefix == false. Currently, because we are returning an empty string
-	// if the path we are currently parsing is equal to the root path, when we attempt to retrieve the element
-	// we receive the error "expr expression is nil".
 	if len(hP) == 0 {
+		// If prefix is false and HierarchyPath is empty, return '.' to represent the current directory in a relative path.
+		// This convention avoids errors (e.g., "expr expression is nil") when retrieving elements from an empty path.
+		if !prefix {
+			return "."
+		}
 		return strHP.String()
 	}
+
 	for i, elem := range hP {
 		if i != 0 {
 			strHP.WriteString(sep)

utils/coreutils_test.go

@@ -905,7 +905,7 @@ func TestHierarchyPathAsString(t *testing.T) {
 			hP:       HierarchyPath{},
 			sep:      "/",
 			prefix:   false,
-			expected: "",
+			expected: ".",
 		},
 		{
 			name:     "Empty HierarchyPath with prefix",
@@ -961,7 +961,7 @@ func TestHierarchyPathAsString(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			if received := tt.hP.AsString(tt.sep, tt.prefix); received != tt.expected {
-				t.Errorf("expected %s, received %s", tt.expected, received)
+				t.Errorf("expected <%s>, received <%s>", tt.expected, received)
 			}
 		})
 	}