NASA's guidelines are not written in blood, but certainly in lost spacecraft. The most famous is the Mars Climate Orbiter that was lost due to ground system and orbiter using different units of measurement, but that's not the only example [1]
Only one of those particularly affected guidelines. After, anything that might end up in a pure oxygen atmosphere had to be non-inflammable, and very uncomfortable.
I can think of at least three NASA missions that resulted in deaths: Apollo 1[1], and the Challenger[2] and Columbia[3] space shuttles.
[1] https://en.wikipedia.org/wiki/Apollo_1
[2] https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disas...
[3] https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...