Newer PyBigwig cannot both read and write.

libhts/libhts.py

@@ -210,7 +210,8 @@ def make_empty_bigwig(filename, chrom_sizes):
     """
     bw_out = pyBigWig.open(filename, "w")
     bw_out.addHeader(list(chrom_sizes.items()))
-    for (chrom, chrom_len) in bw_out.chroms().items():
+    # for (chrom, chrom_len) in bw_out.chroms().items():
+    for (chrom, chrom_len) in chrom_sizes.items():
         bw_out.addEntries(
             chrom, 0,
             values=np.nan_to_num(np.zeros(chrom_len)[0::10]),