Fix typo discpline to discipline

sections/errorhandling/catchunhandledpromiserejection.md

@@ -4,7 +4,7 @@
 
 ### One Paragraph Explainer
 
-Typically, most of modern Node.JS/Express application code runs within promises – whether within the .then handler, a function callback or in a catch block. Suprisingly, unless a developer remembered to add a .catch clause, errors thrown at these places disappear, even not by app.uncaughtException.  Recent versions of Node added a warning message when an unhandled rejection pops, though this might help to notice when things go wrong but it's obviously not a proper error handling. The straightforward solution is to never forget adding .catch clause within each promise chain call and redirect to a centralized error handler. However building your error handling strategy only on developer’s discpline is somewhat fragile. Consequently, it’s highly recommended using a graceful fallback and subscribe to process.on(‘unhandledRejection’, callback) – this will ensure that any promise error, if not handled locally, will get its treatment.
+Typically, most of modern Node.JS/Express application code runs within promises – whether within the .then handler, a function callback or in a catch block. Suprisingly, unless a developer remembered to add a .catch clause, errors thrown at these places disappear, even not by app.uncaughtException.  Recent versions of Node added a warning message when an unhandled rejection pops, though this might help to notice when things go wrong but it's obviously not a proper error handling. The straightforward solution is to never forget adding .catch clause within each promise chain call and redirect to a centralized error handler. However building your error handling strategy only on developer’s discipline is somewhat fragile. Consequently, it’s highly recommended using a graceful fallback and subscribe to process.on(‘unhandledRejection’, callback) – this will ensure that any promise error, if not handled locally, will get its treatment.
 
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