Fix emailing on crash

Author: jfy133

main.nf

@@ -2925,8 +2925,10 @@ workflow.onComplete {
             log.info "[nf-core/eager] Sent summary e-mail to $email_address (sendmail)"
         } catch (all) {
             // Catch failures and try with plaintext
-              def mail_cmd = [ 'mail', '-s', subject, '--content-type=text/html', email_address ]
-              if ( mqc_report.size() <= params.max_multiqc_email_size.toBytes() ) {
+            def mail_cmd = [ 'mail', '-s', subject, '--content-type=text/html', email_address ]
+            if (mqc_report == NULL) {
+                log.warn "[nf-core/eager] Could not attach MultiQC report to summary email"
+            } else if ( mqc_report.size() <= params.max_multiqc_email_size.toBytes() ) {
                 mail_cmd += [ '-A', mqc_report ]
             }
             mail_cmd.execute() << email_html