fix: import non-existant package

interp/src.go

@@ -191,7 +191,8 @@ func effectivePkg(root, path string) string {
 	for i := 0; i < len(splitPath); i++ {
 		part := splitPath[len(splitPath)-1-i]
 
-		if part == splitRoot[len(splitRoot)-1-rootIndex] && i != 0 {
+		index := len(splitRoot) - 1 - rootIndex
+		if index > 0 && part == splitRoot[index] && i != 0 {
 			prevRootIndex = rootIndex
 			rootIndex++
 		} else if prevRootIndex == rootIndex {

interp/src_test.go

@@ -26,6 +26,12 @@ func Test_effectivePkg(t *testing.T) {
 			path:     "vendor/guthib.com/containous/vin",
 			expected: "github.com/foo/plugin/vendor/guthib.com/containous/fromage/vendor/guthib.com/containous/vin",
 		},
+		{
+			desc:     "path is non-existent",
+			root:     "foo",
+			path:     "githib.com/foo/app",
+			expected: "foo/githib.com/foo/app",
+		},
 	}
 
 	for _, test := range testCases {