How long does God's anger last? Bible Contradictions

This Bible contradiction is from the Skeptic's Annotated Bible.

Verses

God's anger lasts for just a moment.

Psalm 30:5 View context

For his anger [endureth but] a moment; in his favour [is] life: weeping may endure for a night, but joy [cometh] in the morning.

God's anger lasts a long time.

Numbers 32:13 View context

And the LORD'S anger was kindled against Israel, and he made them wander in the wilderness forty years, until all the generation, that had done evil in the sight of the LORD, was consumed.

God's anger doesn't last forever.

Jeremiah 3:12 View context

Go and proclaim these words toward the north, and say, Return, thou backsliding Israel, saith the LORD; [and] I will not cause mine anger to fall upon you: for I [am] merciful, saith the LORD, [and] I will not keep [anger] for ever.

God's anger lasts forever.

Jeremiah 17:4 View context

And thou, even thyself, shalt discontinue from thine heritage that I gave thee; and I will cause thee to serve thine enemies in the land which thou knowest not: for ye have kindled a fire in mine anger, [which] shall burn for ever.

Malachi 1:4 View context

Whereas Edom saith, We are impoverished, but we will return and build the desolate places; thus saith the LORD of hosts, They shall build, but I will throw down; and they shall call them, The border of wickedness, and, The people against whom the LORD hath indignation for ever.