How to suppress server errors in Craft? On certain pages of my site, I download and display resized (using the Imager plugin) images from remote site.

Now, sometimes that remote site returns error and in such case Imager is throwing exceptions, blocking the whole page from being viewed.

Now, is there a way to suppress server errors when possible, e.g. write them to log file and don't stop page processing?

devMode is set to false.
It depends on the type of errors that are being thrown.  If they are Twig/template errors, then you can can set the suppressTemplateErrors config setting to true and they will simply get logged and the page request will continue as usual.

If they are non-Twig exceptions, then you'd have to do something more fancy like make a plugin that's essentially a facade for the Imager plugin and wraps all of it's calls in a try/catch block that just swallows any exceptions.

Or make a pull request that added support for it to the plugin itself.