process: check env->EmitProcessEnvWarning() last

Calling env->EmitProcessEnvWarning() prevents additional warnings
from being set it should therefore be called only if a warning will
emit.

PR-URL: #25575
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

src/node_env_var.cc

@@ -72,8 +72,12 @@ static void EnvSetter(Local<Name> property,
                       Local<Value> value,
                       const PropertyCallbackInfo<Value>& info) {
   Environment* env = Environment::GetCurrent(info);
-  if (env->options()->pending_deprecation && env->EmitProcessEnvWarning() &&
-      !value->IsString() && !value->IsNumber() && !value->IsBoolean()) {
+  // calling env->EmitProcessEnvWarning() sets a variable indicating that
+  // warnings have been emitted. It should be called last after other
+  // conditions leading to a warning have been met.
+  if (env->options()->pending_deprecation && !value->IsString() &&
+      !value->IsNumber() && !value->IsBoolean() &&
+      env->EmitProcessEnvWarning()) {
     if (ProcessEmitDeprecationWarning(
             env,
             "Assigning any value other than a string, number, or boolean to a "

test/parallel/test-process-env-deprecation.js

@@ -12,5 +12,9 @@ common.expectWarning(
   'DEP0104'
 );
 
+// Make sure setting a valid environment variable doesn't
+// result in warning being suppressed, see:
+// https://github.com/nodejs/node/pull/25157
+process.env.FOO = 'apple';
 process.env.ABC = undefined;
 assert.strictEqual(process.env.ABC, 'undefined');