Fix memory leak

This fixes oss-fuzz #47527

Author: dstogov

Zend/zend_opcode.c

@@ -826,6 +826,8 @@ static void emit_live_range(
 				/* The use might have been optimized away, in which case we will hit the def
 				 * instead. */
 				if (use_opline->opcode == ZEND_COPY_TMP && use_opline->result.var == rt_var_num) {
+					start = def_opline + 1 - op_array->opcodes;
+					emit_live_range_raw(op_array, var_num, kind, start, end);
 					return;
 				}
 			} while (!(

ext/opcache/tests/opt/coalesce_002.phpt

@@ -0,0 +1,22 @@
+--TEST--
+COALESCE optimization
+--INI--
+opcache.enable=1
+opcache.enable_cli=1
+opcache.optimization_level=-1
+--FILE--
+<?php
+function t() {
+    $y[" $a "] ??= var_dump();
+}
+t();
+?>
+--EXPECTF--
+Warning: Undefined variable $a in %scoalesce_002.php on line 3
+
+Fatal error: Uncaught ArgumentCountError: var_dump() expects at least 1 argument, 0 given in %scoalesce_002.php:3
+Stack trace:
+#0 %scoalesce_002.php(3): var_dump()
+#1 %scoalesce_002.php(5): t()
+#2 {main}
+  thrown in %scoalesce_002.php on line 3