Oh man that's embarrassing... okay so yes I found the complete error message. Copied below:
Arduino: 1.8.8 (Mac OS X), TD: 1.45, Board: "Teensy 3.2 / 3.1, Serial, 96 MHz (overclock), Faster, US English"
/Users/zenstudio/Downloads/Arduino Libraries/midithing-master/firmware/MIDIClass.ino: In member function 'bool MIDICV::ChannelExists(byte, byte, byte)':
MIDIClass:340: warning: unused variable 'i'
int i;
^
MIDILearn: In function 'byte checkMenuMode(byte)':
MIDILearn:414: warning: control reaches end of non-void function
}
^
Sketch uses 28496 bytes (10%) of program storage space. Maximum is 262144 bytes.
Global variables use 5508 bytes (8%) of dynamic memory, leaving 60028 bytes for local variables. Maximum is 65536 bytes.
avrdude: AVR Part "mk20dx256" not found.
Valid parts are:
uc3a0512 = AT32UC3A0512
c128 = AT90CAN128
c32 = AT90CAN32
c64 = AT90CAN64
pwm2 = AT90PWM2
pwm216 = AT90PWM216
pwm2b = AT90PWM2B
pwm3 = AT90PWM3
pwm316 = AT90PWM316
pwm3b = AT90PWM3B
1200 = AT90S1200
2313 = AT90S2313
2333 = AT90S2333
2343 = AT90S2343
4414 = AT90S4414
4433 = AT90S4433
4434 = AT90S4434
8515 = AT90S8515
8535 = AT90S8535
usb1286 = AT90USB1286
usb1287 = AT90USB1287
usb162 = AT90USB162
usb646 = AT90USB646
usb647 = AT90USB647
usb82 = AT90USB82
m103 = ATmega103
m128 = ATmega128
m1280 = ATmega1280
m1281 = ATmega1281
m1284 = ATmega1284
m1284p = ATmega1284P
m1284rfr2 = ATmega1284RFR2
m128rfa1 = ATmega128RFA1
m128rfr2 = ATmega128RFR2
m16 = ATmega16
m161 = ATmega161
m162 = ATmega162
m163 = ATmega163
m164p = ATmega164P
m168 = ATmega168
m168p = ATmega168P
m168pb = ATmega168PB
m169 = ATmega169
m16u2 = ATmega16U2
m2560 = ATmega2560
m2561 = ATmega2561
m2564rfr2 = ATmega2564RFR2
m256rfr2 = ATmega256RFR2
m32 = ATmega32
m3208 = ATmega3208
m3209 = ATmega3209
m324p = ATmega324P
m324pa = ATmega324PA
m325 = ATmega325
m3250 = ATmega3250
m328 = ATmega328
m328p = ATmega328P
m328pb = ATmega328PB
m329 = ATmega329
m3290 = ATmega3290
m3290p = ATmega3290P
m329p = ATmega329P
m32m1 = ATmega32M1
m32u2 = ATmega32U2
m32u4 = ATmega32U4
m406 = ATMEGA406
m48 = ATmega48
m4808 = ATmega4808
m4809 = ATmega4809
m48p = ATmega48P
m48pb = ATmega48PB
m64 = ATmega64
m640 = ATmega640
m644 = ATmega644
m644p = ATmega644P
m644rfr2 = ATmega644RFR2
m645 = ATmega645
m6450 = ATmega6450
m649 = ATmega649
m6490 = ATmega6490
m64m1 = ATmega64M1
m64rfr2 = ATmega64RFR2
m8 = ATmega8
m8515 = ATmega8515
m8535 = ATmega8535
m88 = ATmega88
m88p = ATmega88P
m88pb = ATmega88PB
m8u2 = ATmega8U2
t10 = ATtiny10
t11 = ATtiny11
t12 = ATtiny12
t13 = ATtiny13
t15 = ATtiny15
t1604 = ATtiny1604
t1606 = ATtiny1606
t1607 = ATtiny1607
t1614 = ATtiny1614
t1616 = ATtiny1616
t1617 = ATtiny1617
t1634 = ATtiny1634
t20 = ATtiny20
t202 = ATtiny202
t204 = ATtiny204
t212 = ATtiny212
t214 = ATtiny214
t2313 = ATtiny2313
t24 = ATtiny24
t25 = ATtiny25
t26 = ATtiny26
t261 = ATtiny261
t28 = ATtiny28
t3214 = ATtiny3214
t3216 = ATtiny3216
t3217 = ATtiny3217
t4 = ATtiny4
t40 = ATtiny40
t402 = ATtiny402
t404 = ATtiny404
t406 = ATtiny406
t412 = ATtiny412
t414 = ATtiny414
t416 = ATtiny416
t417 = ATtiny417
t4313 = ATtiny4313
t43u = ATtiny43u
t44 = ATtiny44
t441 = ATtiny441
t45 = ATtiny45
t461 = ATtiny461
t5 = ATtiny5
t804 = ATtiny804
t806 = ATtiny806
t807 = ATtiny807
t814 = ATtiny814
t816 = ATtiny816
t817 = ATtiny817
t84 = ATtiny84
t841 = ATtiny841
t85 = ATtiny85
t861 = ATtiny861
t88 = ATtiny88
t9 = ATtiny9
x128a1 = ATxmega128A1
x128a1d = ATxmega128A1revD
x128a1u = ATxmega128A1U
x128a3 = ATxmega128A3
x128a3u = ATxmega128A3U
x128a4 = ATxmega128A4
x128a4u = ATxmega128A4U
x128b1 = ATxmega128B1
x128b3 = ATxmega128B3
x128c3 = ATxmega128C3
x128d3 = ATxmega128D3
x128d4 = ATxmega128D4
x16a4 = ATxmega16A4
x16a4u = ATxmega16A4U
x16c4 = ATxmega16C4
x16d4 = ATxmega16D4
x16e5 = ATxmega16E5
x192a1 = ATxmega192A1
x192a3 = ATxmega192A3
x192a3u = ATxmega192A3U
x192c3 = ATxmega192C3
x192d3 = ATxmega192D3
x256a1 = ATxmega256A1
x256a3 = ATxmega256A3
x256a3b = ATxmega256A3B
x256a3bu = ATxmega256A3BU
x256a3u = ATxmega256A3U
x256c3 = ATxmega256C3
x256d3 = ATxmega256D3
x32a4 = ATxmega32A4
x32a4u = ATxmega32A4U
x32c4 = ATxmega32C4
x32d4 = ATxmega32D4
x32e5 = ATxmega32E5
x384c3 = ATxmega384C3
x384d3 = ATxmega384D3
x64a1 = ATxmega64A1
x64a1u = ATxmega64A1U
x64a3 = ATxmega64A3
x64a3u = ATxmega64A3U
x64a4 = ATxmega64A4
x64a4u = ATxmega64A4U
x64b1 = ATxmega64B1
x64b3 = ATxmega64B3
x64c3 = ATxmega64C3
x64d3 = ATxmega64D3
x64d4 = ATxmega64D4
x8e5 = ATxmega8E5
ucr2 = deprecated, use 'uc3a0512'
An error occurred while uploading the sketch
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.