Treat empty env variables has undefined (#1586)

Author: jderusse

src/Core/CHANGELOG.md

@@ -6,6 +6,10 @@
 
 - Allow passing explicit null values for optional fields of input objects
 
+### Fixed
+
+- Treat empty env variable as undefined
+
 ## 1.20.0
 
 ### Added

src/Core/src/Configuration.php

@@ -195,7 +195,8 @@ private static function parseEnvironmentVariables(array $options): array
                 // Read environment files
                 $envVariableNames = (array) $envVariableNames;
                 foreach ($envVariableNames as $envVariableName) {
-                    if (null !== $envVariableValue = EnvVar::get($envVariableName)) {
+                    $envVariableValue = EnvVar::get($envVariableName);
+                    if (null !== $envVariableValue && '' !== $envVariableValue) {
                         $options[$option] = $envVariableValue;
 
                         break;