added fix for zero length alias

jen/file.go

@@ -247,5 +247,10 @@ func guessAlias(path string) string {
 		alias = alias[runeLen:]
 	}
 
+	// If path part was all digits, we may be left with an empty string. In this case use "pkg" as the alias.
+	if alias == "" {
+		alias = "pkg"
+	}
+
 	return alias
 }

jen/file_test.go

@@ -22,6 +22,7 @@ func TestGuessAlias(t *testing.T) {
 		"a/foo-go":      "foogo",
 		"123a":          "a",
 		"a/321a.b":      "ab",
+		"a/123":         "pkg",
 	}
 	for path, expected := range data {
 		if guessAlias(path) != expected {