src: terminate correctly double-quote in env variable

PR-URL: nodejs#51510
Fixes: nodejs#51508
Reviewed-By: Yagiz Nizipli <yagiz.nizipli@sentry.io>
Reviewed-By: Debadree Chatterjee <debadree333@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

src/node_dotenv.cc

@@ -142,7 +142,7 @@ void Dotenv::ParseLine(const std::string_view line) {
     auto quote_character = value[quotation_index];
     value.erase(0, 1);
 
-    auto end_quotation_index = value.find_last_of(quote_character);
+    auto end_quotation_index = value.find(quote_character);
 
     // We couldn't find the closing quotation character. Terminate.
     if (end_quotation_index == std::string::npos) {

test/fixtures/dotenv/valid.env

@@ -33,3 +33,4 @@ RETAIN_INNER_QUOTES_AS_BACKTICKS=`{"foo": "bar's"}`
 TRIM_SPACE_FROM_UNQUOTED=    some spaced out string
 EMAIL=therealnerdybeast@example.tld
     SPACED_KEY = parsed
+EDGE_CASE_INLINE_COMMENTS="VALUE1" # or "VALUE2" or "VALUE3"

test/parallel/test-dotenv.js

@@ -68,3 +68,5 @@ assert.strictEqual(process.env.TRIM_SPACE_FROM_UNQUOTED, 'some spaced out string
 assert.strictEqual(process.env.EMAIL, 'therealnerdybeast@example.tld');
 // Parses keys and values surrounded by spaces
 assert.strictEqual(process.env.SPACED_KEY, 'parsed');
+// Parse inline comments correctly when multiple quotes
+assert.strictEqual(process.env.EDGE_CASE_INLINE_COMMENTS, 'VALUE1');