Improve error messages

native-maven-plugin/src/main/java/org/graalvm/buildtools/maven/config/AbstractMergeAgentFilesMojo.java

@@ -74,8 +74,9 @@ private void initializeMergerExecutable() throws MojoExecutionException {
  String nativeImageConfigureFileName = nativeImageConfigureFileName();
  File mergerExecutable = new File(nativeImageExecutable.getParentFile(), nativeImageConfigureFileName);
  if (!mergerExecutable.exists()) {
- throw new MojoExecutionException("'" + nativeImageConfigureFileName + "' tool was not found in the GraalVM JDK at '" + nativeImageExecutable.getParentFile().getParentFile() + "'." +
- "This probably means that you are using a GraalVM distribution that is not fully supported by the Native Build Tools."
+ throw new MojoExecutionException("The '" + nativeImageConfigureFileName + "' tool was not found in the GraalVM JDK at '" + nativeImageExecutable.getParentFile().getParentFile() + "'." +
+ "This probably means that you are using a GraalVM distribution that is not fully supported by the Native Build Tools. " +
+ "Please try again, for example, with Oracle GraalVM or GraalVM Community Edition."
  );
  }
 

native-maven-plugin/src/main/java/org/graalvm/buildtools/utils/NativeImageConfigurationUtils.java

@@ -128,8 +128,8 @@ public static Path getNativeImage(Logger logger) throws MojoExecutionException {
  }
 
  if (nativeImage == null) {
- throw new RuntimeException("GraalVM native-image is missing on your system. " + System.lineSeparator() +
- "Make sure that GRAALVM_HOME environment variable is present.");
+ throw new RuntimeException("The 'native-image' tool was not found on your system. " + System.lineSeparator() +
+ "Make sure that the JAVA_HOME or GRAALVM_HOME environment variables point to a GraalVM JDK, or that 'native-image' is on the system path.");
  }
 
  nativeImageExeCache = nativeImage;