fix: handle unexpected connection termination error in error listener

Signed-off-by: Ramachandran Mani <[email protected]>

Author: rchandranmani

lib/postgresql.js

@@ -103,11 +103,19 @@ function PostgreSQL(postgresql, settings) {
 function attachErrorHandler(settings, pg) {
   if (settings.onError) {
     if (settings.onError === 'ignore') {
-      pg.on('error', function(err) {
-        debug(err);
-      });
+      // Check if the error handler is already attached
+      // to avoid possible memory leak
+      if (!pg.listenerCount('error')) {
+        pg.on('error', function(err) {
+          debug(err);
+        });
+      }
     } else {
-      pg.on('error', settings.onError);
+      // Check if the error handler is already attached
+      // to avoid possible memory leak
+      if (!pg.listenerCount('error')) {
+        pg.on('error', settings.onError);
+      }
     }
   }
 }
@@ -165,8 +173,6 @@ PostgreSQL.prototype.executeSQL = function(sql, params, options, callback) {
       // Release the connection back to the pool.
       if (releaseCb) {
         releaseCb(err);
-        // Remove error event listener to avoid possible memory leak
-        connection.removeAllListeners('error');
       }
       let result = null;
       if (data) {