Add Flow#raise_on_error! as a convenience method

lib/rackstash/flow.rb

@@ -279,6 +279,14 @@ module Rackstash
       raise_on_error?
     end
 
+    # Set the {#raise_on_error} flag to true in order to re-raise any exceptions
+    # which occured during logging.
+    #
+    # @see raise_on_error
+    def raise_on_error!
+      self.raise_on_error = true
+    end
+
     # @return [Bool] `true` if we re-raise any occured errors after logging them
     #   to the {#error_flow}. This can aid in debugging. By default, i.e., with
     #   {#raise_on_error?} being `false`, we swallow errors  after logging them

spec/rackstash/flow_spec.rb

@@ -374,6 +374,14 @@ RSpec.describe Rackstash::Flow do
     end
   end
 
+  describe '#raise_on_error!' do
+    it 'sets the flag to true' do
+      expect { flow.raise_on_error! }.to change { flow.raise_on_error? }
+        .from(false)
+        .to(true)
+    end
+  end
+
   describe '#reopen' do
     it 'calls adapter#reopen' do
       expect(adapter).to receive(:reopen).and_return(true)