Fix error messages and overhaul pretty printing

Fixes #115
11 jobs for PR/issue-115 in 52 minutes and 43 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Test
passed #603956
x86_64-freebsd
test:freebsd:latest

00:25:52

passed #603955
x86_64-freebsd
test:freebsd:recommended

00:26:50

passed #603947
x86_64-linux
test:linux:bootstrap_script

00:05:00

passed #603949
x86_64-linux
test:linux:latest

00:22:01

passed #603948
x86_64-linux
test:linux:recommended

00:23:44

passed #603950
x86_64-linux
test:linux:recommended:32bit

00:21:31

manual #603952
aarch64-linux allowed to fail manual
test:linux:recommended:aarch64
manual #603951
armv7-linux allowed to fail manual
test:linux:recommended:armv7
passed #603946
x86_64-linux
test:linux:stack

00:18:27

passed #603954
x86_64-darwin
test:mac:latest

00:16:36

passed #603953
x86_64-darwin
test:mac:recommended

00:18:50