fix env var check

Author: jcschaff

build.py

@@ -14,10 +14,10 @@ def run_command(command: str, cwd: Path, env: Mapping[str, str]) -> None:
 
 def check_env() -> Mapping[str, str]:
     # print the path environment variable
-    PATH: str = os.environ["PATH"]
-    JAVA_HOME: str | None = os.environ["JAVA_HOME"] or None
-    GRAALVM_HOME: str | None = os.environ["GRAALVM_HOME"] or None
-    MAVEN_HOME: str | None = os.environ["MAVEN_HOME"] or None
+    PATH: str = os.getenv("PATH", "")
+    JAVA_HOME: str | None = os.getenv("JAVA_HOME")
+    GRAALVM_HOME: str | None = os.getenv("GRAALVM_HOME")
+    MAVEN_HOME: str | None = os.getenv("MAVEN_HOME")
     if JAVA_HOME is None and GRAALVM_HOME is None:
         print("JAVA_HOME or GRAALVM_HOME environment variable must be set")
         sys.exit(1)