TypeError: Cannot read property 'totalConnections' of undefined

Hi,

We are developing an application and using mariadb connection pools to access our database. The project is on my laptop but the database server is on a different machine which is in the same LAN with my laptop.

I left the node process running for an hour or so and when I returned and tried to use the application (without restarting it) I saw some connection errors:

(node:10751) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'totalConnections' of undefined
at checkPoolSize (/home/mehmet/development/user-manager/node_modules/mariadb/lib/pool.js:502:39)
at conn.connect.then.catch.err (/home/mehmet/development/user-manager/node_modules/mariadb/lib/pool.js:378:23)
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:189:7)
(node:10751) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was
not handled with .catch(). (rejection id: 3)
(node:10751) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
(node:10751) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'totalConnections' of undefined
at checkPoolSize (/home/mehmet/development/user-manager/node_modules/mariadb/lib/pool.js:502:39)
at conn.connect.then.catch.err (/home/mehmet/development/user-manager/node_modules/mariadb/lib/pool.js:378:23)
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:189:7)
(node:10751) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was
not handled with .catch(). (rejection id: 5)
/home/mehmet/development/user-manager/node_modules/mariadb/lib/pool.js:502
if (!connectionInCreation && this.totalConnections() < opts.connectionLimit && !closed) {
^

TypeError: Cannot read property 'totalConnections' of undefined
at checkPoolSize (/home/mehmet/development/user-manager/node_modules/mariadb/lib/pool.js:502:39)
at Connection.conn.on.err (/home/mehmet/development/user-manager/node_modules/mariadb/lib/pool.js:490:21)
at emitOne (events.js:116:13)
at Connection.emit (events.js:211:7)
at /home/mehmet/development/user-manager/node_modules/mariadb/lib/connection.js:1128:16
at Connection._socketErrorHandler (/home/mehmet/development/user-manager/node_modules/mariadb/lib/connection.js:1093:9)
at emitOne (events.js:116:13)
at Socket.emit (events.js:211:7)
at emitErrorNT (internal/streams/destroy.js:66:8)
at _combinedTickCallback (internal/process/next_tick.js:139:11)

It seems somehow the internal pool variables are nullified, like garbage collected. Have you ever seen something like this before?