E001: Empty Catch Block
This error is emitted when a try expression has a catch block that does not contain any case handlers.
A try expression should be followed by some mechanism to handle any exceptions thrown. Typically a catch expression follows the try and pattern matches on any expected exceptions. For example:
try
println("hello")
catch
case e: Exception => ???
It is also possible to follow a try immediately by a finally - letting the exception propagate - but still allowing for some clean up in finally:
try
println("hello")
finally
// perform your cleanup here!
It is recommended to use the NonFatal extractor to catch all exceptions as it correctly handles transfer functions like return.
Example
def example() =
try println("hello")
catch { }
Error
-- [E001] Syntax Error: example.scala:3:2 --------------------------------------
3 | catch { }
| ^^^^^^^^^
| The catch block does not contain a valid expression, try
| adding a case like - case e: Exception => to the block
|-----------------------------------------------------------------------------
| Explanation (enabled by `-explain`)
|- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
| A try expression should be followed by some mechanism to handle any exceptions
| thrown. Typically a catch expression follows the try and pattern matches
| on any expected exceptions. For example:
|
| import scala.util.control.NonFatal
|
| try println("hello") catch {
| case NonFatal(e) => ???
| }
|
| It is also possible to follow a try immediately by a finally - letting the
| exception propagate - but still allowing for some clean up in finally:
|
| try println("hello") finally {
| // perform your cleanup here!
| }
|
| It is recommended to use the NonFatal extractor to catch all exceptions as it
| correctly handles transfer functions like return.
-----------------------------------------------------------------------------
Solution
// Remove redundant 'try' block
def example() =
println("hello")
// Alternative: Add a case handler to catch exceptions
import scala.util.control.NonFatal
def example() =
try println("hello")
catch { case NonFatal(e) => println(s"Caught: $e") }
// Alternative: use finally instead if you only need cleanup
def example() =
try println("hello")
finally println("cleanup")
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