Address parse errors while using getVar to calculate dependency information

classes/cargo.bbclass

@@ -5,7 +5,7 @@ export CARGO_HOME = "${WORKDIR}/cargo_home"
 
 def cargo_base_dep(d):
     deps = ""
-    if not d.getVar('INHIBIT_DEFAULT_DEPS') and not d.getVar('INHIBIT_CARGO_DEP'):
+    if not d.getVar('INHIBIT_DEFAULT_DEPS', True) and not d.getVar('INHIBIT_CARGO_DEP', True):
         deps += " cargo-native"
     return deps
 

classes/rust-bin.bbclass

@@ -23,7 +23,7 @@ OVERLAP_LIBS = "\
     rand \
 "
 def get_overlap_deps(d):
-    deps = d.getVar("DEPENDS").split()
+    deps = d.getVar("DEPENDS", True).split()
     overlap_deps = []
     for o in d.getVar("OVERLAP_LIBS", True).split():
         l = len([o for dep in deps if (o + '-rs' in dep)])

classes/rust.bbclass

@@ -7,7 +7,7 @@ def rust_base_dep(d):
     # Taken from meta/classes/base.bbclass `base_dep_prepend` and modified to
     # use rust instead of gcc
     deps = ""
-    if not d.getVar('INHIBIT_DEFAULT_RUST_DEPS'):
+    if not d.getVar('INHIBIT_DEFAULT_RUST_DEPS', True):
         if (d.getVar('HOST_SYS', True) != d.getVar('BUILD_SYS', True)):
             deps += " virtual/${TARGET_PREFIX}rust"
         else: