Check local version detection result

Copybara Import from https://github.com/bazelbuild/rules_java/pull/171

BEGIN_PUBLIC
Check local version detection result (#171)

In case the local Java version detection fails, e.g. due to a corrupt installation, skip further processing, as it results in a type error.

Closes #170

Closes #171
END_PUBLIC

COPYBARA_INTEGRATE_REVIEW=https://github.com/bazelbuild/rules_java/pull/171 from bertschneider:fix_local_version_detection 6943c45156edcd521aec87b5080c3cfc8c40f1e5
PiperOrigin-RevId: 607694805
Change-Id: Ib8005f6d40e15034f168121cdee8cebcc4a029f2

toolchains/local_java_repository.bzl

diff --git a/toolchains/local_java_repository.bzl b/toolchains/local_java_repository.bzl
index a49dde2..0a68f19 100644
--- a/toolchains/local_java_repository.bzl
+++ b/toolchains/local_java_repository.bzl
@@ -191,12 +191,17 @@
 
     if not java_bin.exists:
         # Java binary does not exist
+        message = ("Cannot find Java binary {java_binary} in {java_home}; either correct your JAVA_HOME, " +
+                   "PATH or specify Java from remote repository (e.g. " +
+                   "--java_runtime_version=remotejdk_11)")
         repository_ctx.file(
             "BUILD.bazel",
-            _NOJDK_BUILD_TPL.format(
+            _AUTO_CONFIG_ERROR_BUILD_TPL.format(
                 local_jdk = local_java_runtime_name,
-                java_binary = _with_os_extension(repository_ctx, "bin/java"),
-                java_home = java_home,
+                message = repr(message.format(
+                    java_binary = _with_os_extension(repository_ctx, "bin/java"),
+                    java_home = java_home,
+                )),
             ),
             False,
         )
@@ -204,6 +209,21 @@
 
     # Detect version
     version = repository_ctx.attr.version if repository_ctx.attr.version != "" else _detect_java_version(repository_ctx, java_bin)
+    if version == None:
+        # Java version could not be detected
+        message = "Cannot detect Java version of {java_binary} in {java_home}; make sure it points to a valid Java executable"
+        repository_ctx.file(
+            "BUILD.bazel",
+            _AUTO_CONFIG_ERROR_BUILD_TPL.format(
+                local_jdk = local_java_runtime_name,
+                message = repr(message.format(
+                    java_binary = _with_os_extension(repository_ctx, "bin/java"),
+                    java_home = java_home,
+                )),
+            ),
+            False,
+        )
+        return
 
     # Prepare BUILD file using "local_java_runtime" macro
     if repository_ctx.attr.build_file_content and repository_ctx.attr.build_file:
@@ -239,14 +259,12 @@
     for file in repository_ctx.path(java_home).readdir():
         repository_ctx.symlink(file, file.basename)
 
-# Build file template, when JDK does not exist
-_NOJDK_BUILD_TPL = '''load("@rules_java//toolchains:fail_rule.bzl", "fail_rule")
+# Build file template, when JDK could not be detected
+_AUTO_CONFIG_ERROR_BUILD_TPL = '''load("@rules_java//toolchains:fail_rule.bzl", "fail_rule")
 fail_rule(
    name = "jdk",
    header = "Auto-Configuration Error:",
-   message = ("Cannot find Java binary {java_binary} in {java_home}; either correct your JAVA_HOME, " +
-          "PATH or specify Java from remote repository (e.g. " +
-          "--java_runtime_version=remotejdk_11)")
+   message = {message},
 )
 config_setting(
    name = "localjdk_setting",