PropertyExposingClosure returns empty properties when output file doesn't exist yet

During configuration phase, the git.properties file hasn't been generated yet.
Using getOrNull() instead of eager get() prevents exceptions and returns empty
properties until the file is available after task execution.

Author: TheSnoozer

src/main/java/io/github/git/commit/id/gradle/plugin/GitCommitIdPlugin.java

@@ -18,7 +18,7 @@
 package io.github.git.commit.id.gradle.plugin;
 
 import groovy.lang.Closure;
-import java.util.Arrays;
+import java.io.File;
 import java.util.Map;
 import java.util.Properties;
 import org.gradle.api.Plugin;
@@ -94,9 +94,15 @@ public String toString() {
 
         private Properties getProps() {
             try {
+                File outputFile = task.getOutput().getAsFile().getOrNull();
+                if (outputFile == null || !outputFile.exists()) {
+                    // Return empty properties during configuration phase
+                    // when file hasn't been generated yet
+                    return new Properties();
+                }
                 final Properties p = GenericFileManager.readPropertiesAsUtf8(
                     task.getGitCommitIdPluginOutputSettingsExtension().getOutputFormat().get(),
-                    task.getOutput().getAsFile().get()
+                    outputFile
                 );
                 return p;
             } catch (GitCommitIdExecutionException e) {