Propagate errors out of validatePath

The next patch will need to more complicated custom error handling,
so make validatePath return an error and let the caller handle it.

Test: paths_test.go
Change-Id: I4fe11c3f319303d779596709f4819e828b5bdb9b
diff --git a/android/paths_test.go b/android/paths_test.go
index 7e7ecbd..0075798 100644
--- a/android/paths_test.go
+++ b/android/paths_test.go
@@ -112,7 +112,10 @@
 	for _, testCase := range validateSafePathTestCases {
 		t.Run(strings.Join(testCase.in, ","), func(t *testing.T) {
 			ctx := &configErrorWrapper{}
-			out := validateSafePath(ctx, testCase.in...)
+			out, err := validateSafePath(testCase.in...)
+			if err != nil {
+				reportPathError(ctx, err)
+			}
 			check(t, "validateSafePath", p(testCase.in), out, ctx.errors, testCase.out, testCase.err)
 		})
 	}
@@ -122,7 +125,10 @@
 	for _, testCase := range validatePathTestCases {
 		t.Run(strings.Join(testCase.in, ","), func(t *testing.T) {
 			ctx := &configErrorWrapper{}
-			out := validatePath(ctx, testCase.in...)
+			out, err := validatePath(testCase.in...)
+			if err != nil {
+				reportPathError(ctx, err)
+			}
 			check(t, "validatePath", p(testCase.in), out, ctx.errors, testCase.out, testCase.err)
 		})
 	}